title: Actions of the Klenow fragment of DNA polymerase I and some DNA glycosylases on chemically stable analogues of N7-methyl-2'-deoxyguanosine.
abstract: N7-methyl-9-deaza-dG was synthesized and incorporated into oligonucleotides. Thermal melting studies showed that replacement of dG by N7-methyl-9-deaza-dG only slightly decreased DNA duplex stability. Replication of DNA templates containing N7-methyl-9-deaza-dG and the related 7-methyl-7-deaza-dG and 7-deaza-dG by the Klenow fragment of Escherichia coli DNA polymerase I was examined. The dNTP misinsertion frequencies on all three templates were comparably low, although the 7-methyl group significantly slowed down the turnover rates of the polymerase when dCTP was incorporated. The stabilities of N7-methyl-9-deaza-dG and 7-methyl-7-deaza-dG against the actions of formamidopyrimidine DNA glycosylase (Fpg) and human alkyladenine DNA glycosylase (hAAG) were also examined. N7-methyl-9-deaza-dG was stable in the presence of both enzymes. In contrast, 7-methyl-7-deaza-dG was cleaved by Fpg, and possibly by hAAG but at an extremely slow rate. This study suggests that N7-alkyl-9-deaza-dG is a better analogue than 7-alkyl-7-deaza-dG for cellular studies.
authors.affiliation: Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA.
authors.forename: Jagruti
authors.initials: J
authors.lastname: Rana
authors.forename: Haidong
authors.initials: H
authors.lastname: Huang
mesh_terms: D045647:DNA Glycosylases / Q000737:chemistry / Q000378:metabolism*; D004256:DNA Polymerase I / Q000737:chemistry / Q000378:metabolism*; D043382:DNA-Formamidopyrimidine Glycosylase / Q000737:chemistry / Q000378:metabolism; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009841:Oligonucleotides / Q000737:chemistry; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D004256:DNA Polymerase I; C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D043382:DNA-Formamidopyrimidine Glycosylase; D003849:Deoxyguanosine
keywords: Nucleotide analogues